An experiment in cultural interpretation and map revision from Skylab data

There are no author-identified significant results in this report

An experiment in cultural interpretation and map revision from Skylab data

The author has identified the following significant results. S190-A imagery is suitable for input to map compilation and revision at scales from 1:1,000,000 to 1:250,000

Foot-and-Mouth Disease Virus Persists in the Light Zone of Germinal Centres

Foot-and-mouth disease virus (FMDV) is one of the most contagious viruses of animals and is recognised as the most important constraint to international trade in animals and animal products. Two fundamental problems remain to be understood before more effective control measures can be put in place. These problems are the FMDV “carrier state” and the short duration of immunity after vaccination which contrasts with prolonged immunity after natural infection. Here we show by laser capture microdissection in combination with quantitative real-time reverse transcription polymerase chain reaction, immunohistochemical analysis and corroborate by in situ hybridization that FMDV locates rapidly to, and is maintained in, the light zone of germinal centres following primary infection of naïve cattle. We propose that maintenance of non-replicating FMDV in these sites represents a source of persisting infectious virus and also contributes to the generation of long-lasting antibody responses against neutralising epitopes of the virus

Plasmacytoid Dendritic Cells Sequester High Prion Titres at Early Stages of Prion Infection

In most transmissible spongiform encephalopathies prions accumulate in the lymphoreticular system (LRS) long before they are detectable in the central nervous system. While a considerable body of evidence showed that B lymphocytes and follicular dendritic cells play a major role in prion colonization of lymphoid organs, the contribution of various other cell types, including antigen-presenting cells, to the accumulation and the spread of prions in the LRS are not well understood. A comprehensive study to compare prion titers of candidate cell types has not been performed to date, mainly due to limitations in the scope of animal bioassays where prohibitively large numbers of mice would be required to obtain sufficiently accurate data. By taking advantage of quantitative in vitro prion determination and magnetic-activated cell sorting, we studied the kinetics of prion accumulation in various splenic cell types at early stages of prion infection. Robust estimates for infectious titers were obtained by statistical modelling using a generalized linear model. Whilst prions were detectable in B and T lymphocytes and in antigen-presenting cells like dendritic cells and macrophages, highest infectious titers were determined in two cell types that have previously not been associated with prion pathogenesis, plasmacytoid dendritic (pDC) and natural killer (NK) cells. At 30 days after infection, NK cells were more than twice, and pDCs about seven-fold, as infectious as lymphocytes respectively. This result was unexpected since, in accordance to previous reports prion protein, an obligate requirement for prion replication, was undetectable in pDCs. This underscores the importance of prion sequestration and dissemination by antigen-presenting cells which are among the first cells of the immune system to encounter pathogens. We furthermore report the first evidence for a release of prions from lymphocytes and DCs of scrapie-infected mice ex vivo, a process that is associated with a release of exosome-like membrane vesicles

Effects of Cattle and Deer on Regenerating Mixed Conifer Clearcuts

Study began in 1977 at Blodgett Forest Research Station near Georgetown, California, to look at the effects of cattle and deer grazing on mixed conifer plantations. Cattle graze the study area from June 1 until about September 20 each year. Deer are primarily migratory, passing through the study area in March and April and again in October and November each year. The results of treatments on two clearcuts indicate cattle do not harm tree regeneration. Browsing on trees occurred, but no significantly higher numbers of trees were browsed by cattle and deer than by deer alone. White fir seedlings were browsed the most heavily. No trampling damage occurred. Browsing has made no difference in overall tree seedling height or basal diameter between treatments. Brush cover was significantly reduced on grazed treatments on both clearcuts. On 641E, cattle and deer grazing together made a further significant reduction in brush cover over deer grazing alone. The reduction in brush cover has had no effect on tree seedling heights or basal diameters yet. Tree height, basal diameter, and browsing and trampling damage will continue to be monitored, as will brush cover and species composition. Results from this study indicate however, that proper cattle grazing does not harm tree regeneration on young mixed conifer plantations and furthermore cattle grazing may be used as a vegetation management tool in reducing brush on these clearcuts.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Forest Grazing: Past and Future

Livestock have grazed western forests since the 1850's. Policy changes with the inception of government regulation and the end of the free open range brought profound changes in the livestock industry. With increasing demands for timber, recreation and wildlife, grazing began to decline in importance as a use of National Forest ranges. Yet, livestock grazing on forest range is critical to yearlong operations of the ranchers who use them. With proper management livestock can be increasingly important not only as meat and fiber producers, but as part of all land management on national ranges.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Follicular dendritic cell (FDC) precursors in primary lymphoid tissues.

The origin of follicular dendritic cells (FDC) is unresolved, and as such, remains controversial. Based on the migration of Ag-transporting cells (ATC) into lymphoid follicles and the phenotypic similarity between FDC and ATC, one hypothesis is that ATC may represent emigrating FDC precursors. This contrasts with the view that FDC originate from local stromal cells in the secondary lymphoid tissues. Mice homozygous for the severe combined immunodeficiency (prkdc(scid)) mutation (scid) lack FDC. Thus, they provide a powerful tool for assessing de novo generation of FDC. To test whether FDC precursors could be found in bone marrow or fetal liver, scid/scid mice were reconstituted with either: 1) bone marrow cells from (BALB/c x C57BL/6)F1 donors, 2) bone marrow cells from ROSA BL/6 F1 (lacZ-transfected) mice, 3) rat bone marrow cells, or 4) rat fetal liver cells. Six to eight weeks after reconstitution with F1 bone marrow, cells reactive with the FDC-labeling mAb, FDC-M1, also expressed donor class I molecules on their surfaces. Similarly in mice reconstituted with lacZ-transfected bone marrow cells, these cells were also positive for the lacZ gene product. Furthermore, in spleens of animals reconstituted with either rat bone marrow or rat fetal liver, rat FDC were identified using the specifically labeling mAb, ED5. In all cases, host FDC were also present, indicating that scid/scid mice have FDC precursors that will mature in the presence of allogeneic or xenogeneic lymphoid cells. In summary, FDC can be derived from progenitor cells present in primary lymphoid tissues